[xmlsec] encrypt2 - error=45:key is not found

[Michael Hagedorn]

I'm sure this is an absolute beginners question.
But what do I miss:

C:\test\encrypt2\release>encrypt2 encrypt2-doc.xml deskey.bin
func=xmlSecEncCtxEncDataNodeRead:file=..\src\xmlenc.c:line=885:obj=unknown:subj=unknown:error=45:key 
is not found:
func=xmlSecEncCtxXmlEncrypt:file=..\src\xmlenc.c:line=375:obj=unknown:subj=xmlSecEncCtxEncDataNodeRead:error=1:xmlsec 
library function failed:
Error: encryption failed

Used files (encrypt2.c encrypt2-doc.xml deskey.bin) are taken from 
xmlsec1-1.2.11.tar.gz
Btw. same result for encrypt1.c ...

Thanks for your help!
Michael